I bought it (1.8' -> CF adapter) on ebay. It cost me 1.5month of waiting and 30$ (first item mysteriously disappeared on the way from Hong Kong).
Good things: it works with 8gb A-Data turbo 120x (bought from ebay for my camera long time ago. I realized that it is a bit too much for my modest Canon 350d.
Bad things: 1. Original firmware does not recognize the harddrive. It complains and just does not work. Period.
Rockbox does. With limitations.
1. You can connect it to PC only if you turn the player on with USB cable plugged. It is in "Bootloader USB mode" in this case. It is recognized as a plain flashdrive. WMPlayer does not recognize it. So, you have to copy your music by yourself.
If you plug USB while player is working - no hope. It does not recognize the player. I suspect, that Rockbox also has some issues with the hdd size. Also, from time to time Rockbox hangs and needs reboot.
For those who are crazy enough to buy the device (30$ + CF (8gb ~ 80$, newegg)).
First, your player should have rockbox loader.
Second, you have to format the card using FAT32 (xp does it for you, once you select "Format").
Third, you have to remove two pins from the adapter. (It has master/slave switch, I tried with both and it seems like there is no difference.) These pins make the construction too high to fit the space. Here is the link to the auction:
http://cgi.ebay.co.uk/ws/eBayISAPI.d...m=130138988552
Here is the link to the person who is selling this stuff:
http://myworld.ebay.co.uk/linuxbeginner/
Even if it does not show there, you can contact him, he can have some.
Fourth, after installation of the card, plug the USB, turn the player on, copy .rockbox directory from Rockbox website, copy music and enjoy.
P.S. I've got this thing today, so my experience is still somewhat limited. Let me know if you have questions.
P.S. No, I am not affiliated by any way with this guy.